Reactor construction



April 17, 1945. E. c. WENTZ REACTOR CONSTRUCTION Filed Jan. 7, 1943 PHOVAVT Prior AFT INVENTOR Edward C. Wentz.

6% ATTORNEY WITNESSES:

Patented Apr. 17, 1945 REACTOR CON$TRUCTION Edward C. Wcntz, Sha

Westinghouse Electrl pany, East Pittsburgh, Pa., a corporation of Pennsylvania rpsville, Pa, assignor to c & Manufacturing Com- Application January 7, 1943, Serial No. 471,571

(Cl; I'll-42) Claims,

My invention relates to electrical induction apparatus, such as saturable core reactors for controllably varying the reactance of an alternatingcurrent circuit.

It is common practice to provide a saturable core reactor in which a magnetic core structure is associated with an alternating-current winding, and the reactance of the alternating-current winding is varied by superimposing a unidirectional magnetization in the core upon the alternating magnetization. This is done by inducing a unidirectional flux in the core from a directcurrent winding about a portion of the-core structure associated with the alternating-current winding.

It is an object of the invention to provide a saturable core reactor of the above-indicated character that is economical of the materials used, and that includes in a single design both a compact core structure and also a device in which there exists close coupling between the windings in the alternating-current circuit and the windings in the direct-current circuit.

Other objects and advantages of the invention will be apparent from the following description of a preferred embodiment thereof, reference being had to the accompanying drawing, in which:

Figure 1 is a diagrammatic view of a prior art design of saturable core reactor having a compact core structure;

Fig. 2 is a diagrammatic view or a prior art saturable core reactor having close coupling between the windings of the alternating-current circuit and of the direct-current circuit;

Fig. 3 is a perspective view of two core loop parts comprising the core structure used in accordance with the present invention; and

Fig. 4 is a diagrammatic view of the arrangement of the four winding leg of the core structure shown in Fig. 3 and of the direct-current and alternating-current windings thereabout.

Referring to the drawing, Fig. 1 shows a type of construction comprising three winding legs I, 2 and 3 shown in parallel relation and connected at their upper and lower ends by yoke portions 4 and 5, respectively. An alternating-current winding 6 is provided about the core leg I, and a similar alternating-current winding "I is provided about the core leg 3, the two windings 6 and 1 being shown connected in series. A direct-current winding 8 is shown positioned about the remaining leg 2 of the structure. The direct-current winding 8 develops a unidirectional flux in the core structure passing about the two magnetic paths indicated by the dotted line circuits 9, a

portion of the unidirectional flux induced in the winding leg 2 passing about a loop circuit including the winding leg 3 and a portion or the flux passing through a loop circuit including the winding leg I. The windings 6 and l induce an alternating-current flux in the core structure which passes about the loop circuit indicated by the dash line I I including the winding legs I and 3 and the yoke portion 4 and 5 connecting them. By varying the intensity of the unidirectional flux developed in the winding leg 2, the degree of saturation of the winding legs i and 3 may be controllably varied so that the effective alternating flux passing therethrough is limited, and thus the effective reactance of the circuit including the windings 6 and 'i is varied in a well known manner.

In Fig. 2, a core structure isshown having four legs I2, I 3, i4 and I5 connected at opposite ends by the yoke portions l6 and M, respectively. In this structure, two only of the four leg are used as winding legs. An alternating-current winding I8 is positioned about the winding leg i3, and an alternating-current winding I8 is shown posi tioned about the winding leg l4, the two windings being shown as connected in series between terminals 2| and 22. A unidirectional winding 23 is provided having winding turns enclosing both the two winding legs l3 and M, the winding being shown connected between terminals 24 and 25. In this structure, the unidirectional flux passes through the two loop circuits indicated by the dotted lines 28 and 21, one circuit including the winding leg i3 and the outer leg l2 together with their connecting yoke portions i6 and I7, and the other circuit including the winding leg l4 and the outer leg l5 together with their connecting yoke portions. The alternating flux induced from the windings l8 and I9 flows in a loop circuit indicated by the dash line 28 including these two winding leg portions of the core and their connecting yoke portions.

The structure shown in Fig. 1 has an advantage over that shown in Fig. 2, in that the amount of material required in the core is considerably less, there being required only three legs instead of four. The structure shown in Fig. 2 has an advantage over Fig. l, in that the direct-current windings and the alternating-current windings are wound about the same core legs, thus providing a closer coupling between the windings developing the alternating-current flux and the unidirectional flux.

In the structure comprising the Present invention, both of these two advantages are coupled 'and in their general characteristics.

2 2,s74,ose

to Figs. 3 and 4, the core structure in accordance with my invention consists of two structurallyseparate core loops SI and 32 which are similar in cross-sectional area, in length of the circuits, The core part M is provided with two winding leg portions 33 and 34, and the loopstructure 32 is provided with two winding le p rtions 36 and 36.

An alternating-current circuit is provided having winding turns 31 about the winding leg 35 and winding turns 38 about the winding leg 38 of the core part 32, as shown diagrammatically in Fig. 4, these two windings being connected in series between the terminals 39 and 40 and inducing flux in opposite directions in the two winding legs, that is, in the same direction along the path of the loop circuit, so that during any particular half-cycle of alternating current the flux will flw in one direction through the loop circuit, and in the next half-cycle in the opposite direction through the loop circuit. Similar windings BI and 42 are provided on the winding legs 33 and as, respectively, of the core part 3! shown in series between the terminals 58 and 44. For simplicity in the drawing, these various windings 31, 38, GI and 42 are shown as a single turn, but it will be appreciated that they will have a considerable number of turns, the number of turns in'each of the four alternating-current windings being equal. Two direct-current windings t and 436 are provided, the turns of the winding 35 encircling both the winding legs 38 and 35 of the two core portions, and the turns of the winding 46 encircling both the winding legs 36 and 36 of the two core portions, the two direct-current windings s5 and 49 being connected in series between the terminals t! and 48 in such manner as to cause the flux induced from one of the two Wind1ngs.t0 pass upwardly within the magnetic core structure, thus making it possible to materially reduce the amount of material in the core structure over a construction in which it is necessary to provide separate magnetic circuit paths for the unidirectional flux than for the alternating flux, and in which the two paths unite in certain members only of the core.

It will be appreciated that means, not shown, but 'well known in the art, may be provided for varying the intensity of direct current in the saturating or direct-current windin s to thus vary the effective reactance of the alternatin current windings in the circuit. It will likewise be appreciated that the two altemating-current circuits shown in Fig. 4, one including the windlugs 31 and 38, and the other including the windings ll and 42, may be connected either in series circuit relation or in parallel circuit relation to each other. It will also be appreciated that the actual physical relation of the two core parts 3! and 32 to each other and the direction of the unidirectional flux throughout each loop circuit are immaterial so long as the unidirectional fluxes and the alternating fluxes developed have the same relative directions as those disclosed.

Modifications in the arrangement of the circuits and core structures illustrated and described may be made within the spirit of my invention, and I do not wish to be limitefotherwise than by the scope of the appended claims.

I claim as my invention:

1. In a current-limiting. reactance device, in combination, two separate similar core parts each forming a single loop magnetic circuit and each part having two winding legs, alternating-current in the two core legs encircled by it, and downwardly in the other of the two core legs, so as to form unidirectional magnetic flux paths in the two core parts 3| and 32 in the same direction. The number of winding turns of the two windings and 46 will be equal to each other so that the flux induced by each will be alike. With this arrangement of the windings, the uni directional flux in the two core parts ti and 32 will both'be in the same direction about the two 1001p circuits. This is indicated by the lower one of each pair of arrows in Fig. 3 as being in a counterclockwise direction. The instantaneous alternating flux induced by the windings 3'5, 38, ii and as will be in opposite directions about the loop circuits in the two core parts 3| and 32, the direction changing in each part every halfcycle. The arrows shown in core part 3! indicate an alternating-current flux in a counterclockwise direction, and the arrows on the part 32 indicating an altemating-current flux in a clockwise direction. This will be the directions of the alternating flux for a given half-cycle of.

the alternating-current wave. During the next half-cycle, they-will be in the opposite directions.

With this arrangement of the direct-current and alternating-current windings, the net eflect of the alternating fluxes developed in the four altemating-current windings on the two directcurrent coils which enclose both core parts is zero, the voltages normally induced in the different parts of the direct-current windings canceling out.

Thus, in a core produced in accordance with my invention, the paths of the alternating flux windings on the two winding legs of each core part for developing equal alternating fluxes in the two core parts, two direct-current windings, one direct-current winding encircling one of the alternating-current windings on each of the two core parts and the other direct-current winding encircling the remaining ones or the alternatingcurrent windings on each of the two core parts, the connections of the several windings being such that the alternating fluxes in the two core parts are opposite in phase with respect to the unidirectional fluxes in the two core parts so that in one half-cycle of alternating flux the unidirectional and alternating flux are in the same direction in one core part and in opposite directions in the other core part, and these relations reverse in each core part for each successive half-cycle.

2. In a current-limiting reactance device, in combination, two separate similar core parts each forming a single loop magnetic circuit and each part having two winding legs, an altematingcurrent winding on each of the four legs of the core structure, a direct-current winding encircling and closely coupled to two alternating-current windings one on each of the two core structures, a second direct-current winding encircling and closely coupled to the remaining two alternating-current windings, one on each of the two core structures, the several alternating-current windings being designed to. induce equal instantaneous alternating fluxes and the direct-current windings being also designed to induce equal unidirectional fluxes in the several legs of the core structure, the fluxes induced by the direct-current windings being cumulative in both core parts, the instantaneous fluxes induced by the alternating- .current windings being cumulative in each core and of the unidirectional flux are the same paths asrsooe phase relation in the two core parts with respect to the unidirectional flux so that in one halt-cycle of alternating flux the unidirectional and alternating fluxes are in the same direction in one core part and in opposite directions in the other core part, and these relations reverse for each successive half-cycle.

3. In a current-limiting reactance device, in combination, two separate similar core parts each forming a single loop magnetic circuit, two alternating-current windings on each oi'the core parts, a direct-current winding encircling and closely coupled to two alternating-current windings one on each oi the two core parts, a second directcurrent winding encircling and closely coupled to the remaining two'altemating-current windings.

one on each of the two core parts, the four alter-l hating-current windings being designed to induce equal instantaneous alternating fluxes and the two direct-current windings being also designed to induce equal unidirectional fluxes in the two core parts, the fluxes induced by the two directcurrent windings being cumulative in both core parts, the instantaneous fluxes induced by the alternating-current windings being cumulative in each core part with respect to each other and in opposite phase relation in the two core parts with respect to the unidirectional flux so that in one half-cycle of alternating flux the unidirectional and alternating fluxes are in the same direction in one core part and in opposite directions in the other core part, and these relations reverse for 1 each successive halt-cycle.

4. In a current-limiting reactance device, in combination, two separate similar core parts each forming a single magnetic circuit loop, a directcurrent circuit having winding turns pass through the openings oi both of the two magnetic circuit loops and encircling the magnetic circuit 40 I path of both of the two core parts for inducing unidirectional flux in both of said core parts, alternating-current circuit turns passing between the two core parts and through the opening of one of said two core parts and encircling the magnetic circuit path of that core part, and alterhating-current circuit turns passing between the two core parts and through the opening of the other of said two core parts and encircling the magnetic circuit path of that core part, the alterhating-current circuit turns being so arranged that the alternating fluxes induced in the two magnetic circuit loops of the two core parts will be opposite in phase in the two core parts with respect to the direction of the unidirectional flux therein.

5. In a current-limiting reactance device for alternating-current circuits, in combination, two separate core loops of magnetic material forming two similar single magnetic circuit paths having like cross-sectional areas and lengths, a directcurrent circuit having winding turns passing through the openings of both core loops and encircling both magnetic circuit paths for inducing equal unidirectional fluxes in each of the two magnetic circuits, alternating-current circuit means comprising winding turns passing through the openings of the two core loops and between the two core loops and encircling each of the two core loops for inducing equal aitemating fluxes in the two magnetic circuits in phase opposition in the two magnetic circuits so that during each half-cycle of the alternating flux the alternating flux and the unidirectional flux in one of the-two magnetic circuits will be in the same direction and the alternating flux and the unidirectional flux in the other one of the two magnetic circuits will be in opposite directions.

EDWARD C. WENTZ. 

